KREFELD, Germany — Final details have been released on Arden's AJ21, the Jaguar XF conversion, and this German tuner proves that it was worth the wait.

Power can come from a top-of-the-line supercharged 4.5-liter V8 that lays down 550 horsepower, or customers can opt for a more subtle upgrade for the 2.7-liter diesel-6 that increases output to 250 hp from the stock 207-hp figure.

The supercharged 4.5-liter uses a special crankshaft and connecting rods that, when combined with the tuned ECU, help give the V8 the additional power. A high-performance stainless-steel exhaust system and Bilstein sport suspension finish off the list of performance modifications.

The biggest exterior change is the new front end that keeps the engine cooler with a larger grille and intake system. Arden adds a front spoiler, rear bumper, rear spoiler, side skirts and a pair of foglamps that are reminiscent of Audi's latest LED daytime running lights. A set of 21-inch forged Sportline alloys with 255/35ZR21 tires work with 13.4-inch ventilated and punched disc brakes to give the Jag extra stopping power and a meaner stance.

High-grade wood and carbon-fiber trim inserts are available to spice up the interior, which can be customized in a variety of leather and Alcantara upholstery.

Parts are individually priced on Arden's Web site, but the supercharged 4.5-liter engine upgrade and body kit alone will cost the equivalent of $97,000.